Technique to verify underground targets utilizing virtual reality imaging and controlled excavation

ABSTRACT

A system and method for locating and verifying a position of an underground target utilizes a virtual reality display to guide a cutting probe to the target. Initial coordinates of the target may be obtained from prior survey data and a vertical access borehole is excavated at the initial coordinates in a first attempt to verify the target position. If the target it not encountered at the initial coordinates, a lateral sensor is positioned within the vertical access borehole to determine three-dimensional coordinates of the target. A second borehole is then excavated by a cutting head that is guided to the three-dimensional target coordinates with the assistance of a virtual reality display that shows both the target coordinates and a real time position of the cutting head. A down-hole camera or other sensor positioned within the second borehole may verify the presence or condition of the target.

FIELD OF THE INVENTION

The present disclosure generally relates to locating and verifying the position of underground targets utilizing real time virtual reality imaging and data acquisition including Ground Penetrating Radar (GPR), where controlled drilling apparatuses are used to excavate material, such as dirt, rock, or sand. More particularly, the disclosure relates to providing a visual display from 3D modeling in virtual space in addition to excavating stealth boreholes by monitoring, controlling, and recording drilling process information, including the cutting head location within the formation. Drilling process information includes the temperature and pressure of drilling fluids, including fluids and soil composition within an excavation chamber of a drilling apparatus.

BACKGROUND OF THE INVENTION

Location and verification of utilities and other underground targets begins with the location and recording of the target position on the ground surface above the buried target, often with paint markings Initial location on the surface is determined by maps, drawings, signal generators such as Ground Penetrating Radar (“GPR”) or electromagnetic field locators and other means. The surface markings vary in accuracy and occasionally represent false readings where no target exists. Visual verification of the target is normally required if the target is within an excavation dig construction zone where the excavation may expose the target.

Drilling apparatuses are used in the excavation of materials or features, as well as to access such materials or features (such as buried vessels or utility lines). For example, drilling apparatuses are used to excavate dirt, rock, and/or other material. U.S. Pat. No. 6,050,352, issued to the present inventor and incorporated herein by reference in its entirety, is entitled “Drilling Technique Utilizing Drilling Fluids Directed on Low Angle Cutting Faces” and describes one example of a drilling apparatus that utilizes a pressurized drilling fluid and a vacuum to evacuate the slurry.

One excavation process, known as “soft excavation,” pushes a fluid, such as air or water, through a device with a cutting edge. The device expels the fluid at high velocities towards the excavation site. This breaks up the material of the excavation site, which material is then removed by a secondary system such as an airflow system or mechanical extraction process. The use of such technology, however, can lead to the destruction of embedded structures in the excavation site in certain circumstances and can cause excessive excavation and tailings during location of the embedded structure.

Low frequency GPR scanning of the ground surface above a formation produces relatively low-resolution images and false target contacts, especially where previous trenches intersect the region and radar signals bounce off the trench walls or other areas of differing compaction in the formation. During exploration for the target, current art utilizes high pressure fluids for excavation, where destruction of embedded structures and other targets frequently occur because it is sometimes difficult to control the cutting power of the high pressure fluid. The use of a sharp cutting edge and the heavy weight of the device on this edge further compound cutting control issues. As such, utility lines and other structures can be accidentally damaged when using only surface location data and existing soft excavation processes.

Additionally, when using existing methods to locate underground utilities prior to construction, the entire excavation site can be flooded due to poor fluid control from manual operation of the apparatus. Inadequate fluid control can cause fluid to flow into the surrounding formation in a volume sufficient to structurally damage the formation before the excavation slurry is vacuumed from the hole. This can cause a cave-in of the surrounding formation and result in damage to the existing utility conduit or other target.

One technique to compensate for some of the deficiencies of the soft excavation process is to use a concentric piping configuration. A soft excavation process using a concentric piping configuration excavates loosely consolidated geologic formations by applying a partial vacuum to direct the return of the excavation fluids. For example, a partial vacuum may be applied to the cutting head area. This piping configuration may be used to produce stealth boreholes, where “stealth excavation” is a type of minimally intrusive drilling or boring that controls the disturbance of the formation surrounding the borehole.

It is desirous, however, to regulate and control various process parameters such as the flow, pressure, and temperature of the supply and return conduits to the cutting head area. Additionally, monitoring the partial vacuum may also be desirous. Such regulation and control helps to prevent blow outs, infiltration from the formation, or irregular borehole walls. Additionally, as monitoring helps regulate and control the drilling process, it remains desirous for a system that will allow for the monitoring of the process parameters

It is with respect to these and other considerations that embodiments have been made. Also, although relatively specific problems have been discussed, it should be understood that the embodiments should not be limited to solving the specific problems identified in the introduction.

SUMMARY OF THE INVENTION

The virtual reality process described herein locates and verifies the position of underground targets, generates a 3D model in virtual space, and displays an image of the model through a display or viewport. The image allows an excavation probe operator to position and guide the probe to intersect and verify the target. The target may be an existing utility, archeological bury, forensic crime site or any desired point in the formation. The virtual reality image can be displayed on a screen or visor and may be viewed by the target probe operator as well as others.

In one embodiment, data acquisition begins with a ground surface low frequency GPR scan which locates a target but with relatively poor resolution. A vertical access borehole is excavated at a known or calculated x,y coordinate surface location. The vertical hole includes a smooth planar surface to allow required total contact between the face of the formation and a GPR antenna. This requires a hole with a smooth flat plane for at least one side such as a rectangular cross section shape. The controlled stealth excavation process disclosed herein is utilized to excavate the required access hole.

If the target is encountered during the excavation of the initial borehole, it can be verified and the location recorded in x,y,z coordinates. If the target is missed, a GPR antenna can be lowered into the access borehole to scan laterally for the target. The GPR antenna is preferably smaller and operates at a higher frequency than the antenna used with the initial ground surface scan. The higher antenna frequency provides better image resolution, although depth of penetration is reduced with the higher frequency scan. However, because the vertical borehole has been formed near the target, the vertical probe only needs to penetrate a relatively shallow lateral depth. Thus, the higher resolution image generated allows for a precise location of the target (e.g., within an inch). The x,y,z coordinates of the target are then calculated in relation to the surface location of the vertical borehole.

In a further embodiment where verification of the target position is required, a second small diameter probe borehole is excavated where the angle and depth of the hole is calculated to terminate at the determined x,y,z coordinates of the target location. The probe borehole axis is displayed in the virtual reality images to provide the probe operator with real-time location of the cutting head. Once the target is encountered, the excavation apparatus can be withdrawn, and the target can be visually verified and the location recorded for As Built drawings and other uses.

Other methods may be used to acquire data to generate the 3D virtual space model, including using 3D Computer Aided Design (CAD) drawings (such as Autodesk Civil 3D) that provide detailed information about the position and purported depth of utility lines or other underground targets. Alternatively, data to construct the 3D model may be acquired from boreholes formed by other means of excavation.

System control of the drilling process can be provided in several forms. A computer controlled system involves analyzing input data and providing the capability to conduct an automated excavation by balancing an excavation chamber of the cutting head from received data inputs. Balancing the excavation chamber includes controlling physical properties of drilling fluids and gases to produce efficient excavation for a particular soil type or condition. Alternatively, a hard-wired or mechanical processor can follow a predetermined sequence but cannot anticipate problems and modify the procedure during operation, thus requiring human intervention for safety reasons. Standard Operating Procedure (SOP) follows the same predetermined sequence of a hard-wired processor but with added oversight and manual operation by human operators. However, a human operator can be quickly overwhelmed by the combined duties of observing the operations at the site, observing gauges, setting valves, etc.

A combination of control types may be required to oversee the operation and safety of the jobsite. For example, excavation of post holes may be performed by a computerized excavation process where the only functions of the operator relate to starting and stopping the excavator and moving the apparatus to new locations. Alternatively, operation of a vertical utility probe in known soils may utilize a hard-wired or computer processor for control of the drilling apparatus with only safety oversight by a human operator.

The system control process includes mechanical processing such as pressure control and relief valves that follow a procedure such as opening a valve at a preset pressure until the pressure level drops back to within limits, then closing the valve. Some systems may utilize a combination of different control forms, for example an operator of a utility probe may have a menu on a touchpad with a selection of soil types. A hard-wired processor may initiate predetermined criteria for fluid pressures and other properties for balancing the excavation chamber of the probe for that soil type. The operator then evaluates the excavation process and has the capability to adjust properties by either altering the drilling criteria or manually intervening. Emergency manual controls must be available for safety reasons and interruptions from such events as a power failure.

The term processor is defined herein to include digital and analog controls, mechanical automated control, hard-wired processors and other control apparatus that exceed the physical capability of a human operator.

In one preferred embodiment, the present invention comprises a method of excavating a borehole to an underground target point having predetermined three-dimensional coordinates. A cutting head of an excavation probe initiates the borehole at a probe entry point and a real-time three-dimensional position of the cutting head within the formation is displayed on a virtual reality display. The virtual reality display also shows the predetermined underground target point to directionally guide the cutting head to the target point.

In a further embodiment, a method of locating and verifying a position of an underground target includes excavating a vertical access borehole at initial coordinates representing a surface point positioned above the underground target. If the vertical access borehole engages the underground target, then the three-dimensional position of the underground target is verified. If the vertical access borehole does not engage the underground target, then a lateral sensor is lowered into the vertical access borehole to locate and determine three-dimensional coordinates of the underground target. A second borehole is then excavated from a second surface point and is directed into engagement with the underground target to its position. Preferably, a virtual reality display is used to show both the determined three-dimensional coordinates of the underground target as well as the real-time position of the second borehole to help guide a probe cutting head forming the second borehole to the underground target.

In an alternative embodiment, a system for locating and verifying a position of an underground target includes a first drilling apparatus adapted to excavate a vertical access borehole at initial surface coordinates, and a lateral sensor adapted to be positioned within the vertical access borehole to determine three-dimensional coordinates of the underground target. A second drilling apparatus excavates a second borehole extending toward the three-dimensional coordinates of the underground target, and a virtual reality display shows the three-dimensional coordinates of the underground target in relation to a real-time three-dimensional position of a cutting head of the second drilling apparatus to directionally guide the cutting head into engagement with the underground target.

A more complete appreciation of the present invention and its scope can be obtained from understanding the accompanying drawing, which is briefly summarized below, the following detailed description of presently preferred embodiments of the invention, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a field excavation site illustrating components of a virtual reality imaging system.

FIG. 2 is a functional block diagram of the virtual reality imaging system.

FIG. 3 is a flow diagram of a method of virtual reality imaging for location and verification of underground targets as shown in FIG. 1.

FIG. 4 is a cross sectional view of a drilling apparatus of the present invention illustrating schematic monitoring and control features.

FIG. 5 is a functional block diagram of a computing system configured to monitor and control process parameters of the drilling apparatus shown in FIG. 4.

FIG. 6 is a flow diagram of a method of monitoring and controlling the drilling apparatus shown in FIG. 4.

DETAILED DESCRIPTION

FIG. 1 illustrates a field excavation site (500) in an isometric view. A ground surface plane (510) is located above a buried utility target (520). This particular target (520) is linear, however any shape target may be located using this method. The target may also be a virtual-only target. A base point (530) is at a known location including coordinates used in the Global Positioning System (GPS). From the base point (530), the coordinates of any point on the surface plane (510) can be determined by horizontal distances in the x axis (540) and y axis (550) from any point to the base point (530). Vertical coordinates are defined by the z axis (560).

In this embodiment, a surface marking (570) is placed above the target (520) by locating equipment such as Ground Penetrating Radar (“GPR”) which can also display a depth of the target (520). The accuracy of such location varies and cannot typically be relied upon for a precise location of the target (520). Visual verification of the target is normally required prior to construction and involves excavation to expose the target to avoid damage during construction of the utility. The path of construction (580) and the surface marking (570) have a point of intersection (590) on the surface plane (510) whose x and y coordinates can be determined by measurement from the base point (530).

An access hole (600) is excavated vertically starting at the intersection point (590) and penetrates the formation to a purported target depth where the access hole either contacts the target (520) or passes in close proximity to it. If contact occurs, the target (520) is visually verified and the mission is complete. The access hole (600) is preferably formed using a stealth cutting head so that the walls of the hole (600) are smooth and planar. Thus, if the target is missed, a sensor (610) may be lowered into the access hole (600) to determine the lateral distance (620) and direction to the target (520). The lateral sensor (610) may be GPR or another locator-type sensor, but must be accurate to within about an inch in order to locate a target communication lines down to 0.5 inches in diameter (normally the smallest utility lines), so that a probe (630) having a 2-inch diameter can intersect the target (520). In the event that no target is located by the sensor (610), the purported target (520) can be classified as a false target without requiring excessive excavation to come to the same conclusion.

Upon locating the target (520) with the sensor (610), the three-dimensional x,y,z coordinates of the target are recorded and utilized to direct the probe (630) to the coordinates in order to verify the existence (and possibly determine the condition) of the target (520). The probe (630) starts excavating at a probe entry point (640) on the surface plane (510) and is directed toward a contact point (650) with the target (520) by directionally monitoring the excavation angle (660) and directional bearing (670) in relation to the surface plane (510). Additionally, a distance of the cutting head from the probe entry point (640) may also be monitored. In a preferred embodiment, the probe operator is provided with representations of the target (520) and contact point (650) displayed before him in a virtual reality display (e.g., on a computer display screen or within a virtual reality visor worn by the operator). The real-time position of the probe (630) (or a borehole axis formed by the probe) is also displayed on the virtual reality display to help the probe operator guide the probe to the contact point (650).

FIG. 2 is a block diagram of a virtual reality imaging system (400) utilized in the location and verification of underground targets. A computing device (410) provides data analysis from real time inputs and preferably produces 3D ghost imaging of structures within a formation.

The computing device (410) is connected to a database (420) which includes base GPS coordinates (430) and GPR (or other) images (440) that are used to calculate x,y,z coordinates of the target. These target coordinates are then recorded in another portion (450) of the database (420), as described in greater detail with respect to FIG. 3 below. In particular, the computing device (410) utilizes data from the database (420) to provide an image to a display (460) for use during the probe guidance and target verification procedures described above with respect to FIG. 1. In a preferred embodiment, the display (460) is a virtual reality display, such as a visor worn by the probe operator. Specifically, the drilling apparatus (100) communicates with the database (420) through the computing device (410) to locate the point of entry (640) of the probe (630) in the surface plane (510) as shown in FIG. 1. Probe geometry consisting of cutting head depth, drilling angle (660) and bearing (670), as shown in FIG. 1, is provided to the computing device (410) to generate a virtual image of the probe (630) in the display (460), thereby allowing the probe operator to guide the probe cutting head to intercept the contact point (650). Once contacted, the target can be verified and the update image and target coordinates can be saved in the database (420).

FIG. 3 is a flow diagram of a method (800) for locating and verifying the position of underground targets as shown in FIG. 1. The method (800) begins with a ground surface scan (810) above a target to locate its position in x and y coordinates. Alternatively, other position data may be used in step (810), such as detailed civil engineering plans based on 3D CAD drawings. The assumed location is marked on the surface plane (510) as shown in FIG. 1. The next step in method (800) includes excavating a vertical access borehole (820) in an attempt to initially contact the target. The access borehole excavation (820) is started at the marked location (590) on the surface plane (510). If initial target contact is positive at determination (830), e.g., if the vertical access borehole engages the target (520), the target is verified at step (840), such as by visually observing the target through the borehole, and its position is recorded at step (850), such as in database (420). If the initial target contact is negative at determination (830), the method proceeds to lowering data acquisition equipment into the vertical borehole to laterally locate the target at step (860). If the lateral target search is negative at determination (870), it is noted as a false reading at step (880) and recorded at step (850). If the target search (870) is positive, the method proceeds to a calculation (890) of x,y,z coordinates for the target which are preferably recorded (850) as a probe target to be excavated. An optional probe guidance step (900) involves providing imaging based on the x,y,z coordinates calculated in step (890) to allow an operator to guide an excavation probe and achieve target contact at step (910). As described above, the probe guidance step (900) preferably utilizes a virtual reality display so the operator can accurately guide the excavation probe to the target (520). Once the target is contacted in step (910), the target is verified (940) (e.g., by visually observing the target through the borehole) and the updated x,y,z coordinates recorded in step (850).

FIG. 4 illustrates an embodiment of a cutting head (43) of a drilling apparatus (100) having an excavation chamber (1) that is monitored in real time to allow immediate control over physical properties within the chamber (e.g., pressure, temperature, etc.). The excavation chamber (1) is defined as the volume contained by the freshly exposed face of the excavated formation (7), by the interior of the cutting head (43) and conduit (4), and by the boundary of reduced turbulence where laminar flow begins to be perceived in the return flow of drilling fluids and gases. Dynamically balancing the excavation chamber (1) includes controlling physical properties of drilling fluids and gases to produce efficient excavation for a particular soil type or condition. For example, forensic and archeological excavations are required to be as delicate as possible. In embodiments, an inner annulus (44) of the cutting head (43) operates with a reduced pressure in relation to an outer annulus (45) Annular is used herein to denote any shape perimeter, including circular as well as rectangular. As illustrated, a tapered end (2) forms a pressurized annular orifice (3) between an inner conduit (4) and an outer conduit (5) of the cutting head (43). The orifice (3) is positioned behind a cutting edge (8) so that the released flow impinges on a low angle cutting face (6) to dislodge and move formation material (7) from the cutting edge (8) into the excavation chamber (1) where turbulence generates a slurry of the excavated material and promotes discharge up the reduced pressure inner annulus (44) of the inner conduit (4). In embodiments, the cross sectional area of the inner conduit (4) is a large percentage of the total cross sectional area of the cutting head (43) thereby allowing large consolidated objects such as small rocks to be expelled from a drill string connected to the cutting head (43). The term “drill string” is used herein to denote that preferred embodiments of the apparatus may have connecting conduit modules forming a drill string to allow excavation to distances beyond standard lengths of pipe or conduits, especially for horizontal applications. In embodiments, the drilling apparatus (100) may have threaded connections on conduit ends that allow additional lengths of drill string conduit to be added.

An excavation process may begin with dislodgement by the cutting edge (8) of the perimeter of the hole. Next, drilling fluids are directed at the face of the formation and at the low angle cutting face (6). This turns the dislodged material into a turbulent slurry. The properties of the turbulent slurry depend on the amount and type of drilling fluids supplied. In embodiments, the drilling apparatus (100) is rotated during excavation to help increase the efficiency.

Vertical control of the drilling apparatus (100) is useful to help prevent the cutting edge (8) from damaging a target. In embodiments, the cutting edge (8) may be dulled to prevent similar damage. In other applications where excavation is for penetration only and not aimed at a delicate target, the cutting edge (8) and other aspects of the drilling apparatus (100) may be of a more aggressive design.

In embodiments, a relatively small weight-on-bit force is useful with this method as the material being excavated is structurally dissolved by drilling fluids, and the cutting edge generally acts to define the perimeter of the borehole. If desired, however, a larger force may be applied.

Additionally, drilling fluids from a high pressure orifice (39) may excavate portions of the formation. In embodiments, this occurs where the high pressure orifice (39) is directed downward and partly inward toward the center of excavation to prevent migration of fluids into the formation. The high pressure orifice (39) is supplied by a high pressure fluid supply line (40), which is placed in the annular space between the inner conduit (4) and the outer conduit (5) until it nears the cutting face (6). The high pressure fluid then penetrates the wall of the inner conduit (4) and is directed toward the desired location on the face of the formation. The high pressure fluids may project beyond the plane of the cutting head (43). It is preferable to monitor the high pressure projection to prevent unwanted disturbance of the formation beyond the perimeter of the borehole. In embodiments, the high pressure system is normally located between the inner conduit (4) and the outer conduit (5), but may be located anywhere within the drill string.

Excavated material is transported upward through the excavation chamber (1) defined by the inner conduit (4) due to the pressure difference between the excavation chamber (1) and a vacuum chamber (31) located at the top of the drill string. The excavated material is then pushed into the vacuum conduit (32) and transported away from the apparatus and stored or disposed of as tailings.

Turning toward the valve and pumping configuration, an example valve and pumping configuration is illustrated in FIG. 4. The manifold, valve, and pumping configuration illustrated is but one configuration, and those skilled in the art will appreciate that other configurations may be used.

In an embodiment, a constant volume high pressure pump (28) supplies both the high and low pressure drilling fluids. In other embodiments, more than one means of pressurizing the drilling fluids is used. As illustrated, the size of the high pressure orifices (39) is small in comparison to the low pressure annular orifice (3). The smaller an orifice, the higher the back pressure will be from a constant volume pump (28). Other pumps may be used, such as a variable speed drive pump or a centrifugal pump that maintains a constant pressure but varies in the volume of fluids generated.

In an embodiment, high pressure fluids are supplied to high pressure orifices (39) by fluid supply line (25) from the high pressure fluid supply line (40) when high pressure orifice valve (24) is open and high pressure fluid release valve (22) is closed. Low pressure drilling fluids are supplied to the annular orifice (3) when the high pressure fluid release valve (22) is open and the high pressure orifice valve (24) is closed. Additionally, low pressure fluid release valve (16) is opened, and low pressure return valve (20) is closed to allow the low pressure fluid to be directed to the annular orifice (3). Recirculation of drilling fluids is accomplished by opening the low pressure fluid return valve (20) and closing the low pressure fluid release valve (16).

The mixture of liquids and gases supplied to the annular orifice (3) are released from a manifold (9) that allows low pressure drilling fluid (10) and compressed gas or air (11) to be mixed in a desired proportion before flowing toward the annular orifice (3). In an embodiment, the compressed gas or air (11) is released into the manifold (9) from an air valve (13) in air supply line (14). The pressure of the supply line (14) is monitored by an air pressure indicator (15).

In an embodiment, the low pressure drilling fluids (10) are released from the low pressure fluid release valve (16) located in the low pressure fluid supply line (17) whose pressure is monitored by a low pressure fluid pressure indicator (18) and protected by a low pressure safety relief valve (19). A fluid return valve (20) releases unused fluid to a fluid return line (21).

The low pressure fluid supply line (17) is supplied by a high pressure fluid release valve (22) that isolates the low pressure supply line (17) from the high pressure fluid supply line (25). The high pressure fluid supply line (25) has a high pressure fluid pressure indicator (23) and a high pressure orifice valve (24). The high pressure orifice valve (24) is protected by a high pressure safety relief valve (26) on the high pressure fluid supply line (27), where the relief valve (26) opens if the pressure within the fluid supply line (27) exceeds a predetermined threshold value. The high pressure fluid supply line (27) transports drilling fluid from the high pressure pump (28). The high pressure pump (28) is supplied by fluid supply from the recycled return fluid (29) in fluid return line (21). Any needed make-up fluid is provided from the make-up fluid supply (30).

In embodiments, the high pressure fluid supply line (40) has a quick disconnect to allow additional lengths to be added for deeper excavation. Any desired number of high pressure outlets may be used.

Additionally, the drilling fluids may be heated in various ways. For example, heating of drilling fluids may be accomplished by throttling the high pressure fluid release valve (22) to nearly a closed position, which allows a large pressure release across the orifice to generate heat. The energy from the motor that drives the pump is converted to heat across the orifice. This may cause an increase in temperature within the recirculating high pressure boundary. The heated fluid may increase the intensity of cryogenic fluid expansion as the phase change from liquid to gas occurs. In embodiments, the temperature may be monitored to control the valve position. For example, the temperature may be monitored by the fluid temperature indicator (41).

Various monitoring devices or indicators may be used in conjunction with the drilling apparatus (100) to monitor process parameters. In embodiments, this allows for an operator to reproduce the same or similar conditions in the excavation chamber (1) by monitoring indicators and adjusting control of fluids by automated or manual control of valves. In other embodiments, a computing device aggregates the process parameter information for later use.

Indicators may include visual gauges or electronic sensors that communicate process parameter information to a data acquisition unit, computing device, or user. In an embodiment, the manifold (9) has a manifold pressure indicator (12) to monitor pressure within the manifold (9). In other embodiments, a vacuum and pressure indicator (33) monitors the vacuum or pressure in the vacuum chamber (31). The exact location for indicator sensors may differ within the monitored manifolds or conduits. For example, as illustrated, sensors for manifold pressure indicator (12) or vacuum and pressure indicator (33) may be located elsewhere on the drilling apparatus (100).

In an embodiment, a safety limit of 125 psi for compressed air is used. Other configurations can be used where the drilling apparatus (100) is designed and operated to withstand higher pressures. Additionally, low pressure drilling fluids may be limited to 200-600 psi, while high pressure systems may be limited to 3000 to 5000 psi. In embodiments, the large difference in pressure allows for heating of the fluids including use in rapid boiling of cryogenic fluids. The pressures and volumes of fluids used in other embodiments utilizing this method may vary greatly.

In embodiments, accidental overpressures within the vacuum chamber (31) are released by the overpressure release valve (34). The vacuum relief air (35) is released into the vacuum chamber (31) by the vacuum relief valve (36) in order to assist in balancing the excavation chamber.

In other embodiments, visual monitoring may be accomplished through the use of a removable access cap (37) in the top of the drill string. The access cap (37) includes a transparent viewing plate (38) through which light, visual observation, or image recording can take place. This may allow a user to closely document material removed during excavation and to note properties of encountered materials or target utilities during excavation.

FIG. 5 illustrates a processing system (200) that may be used with an embodiment of the drilling apparatus (100). As illustrated, processing system (200) includes a database (202), a processing device (204), an analog/digital converter (206), a communications network (208), and a drilling apparatus (100). The drilling apparatus (100) preferably comprises the drilling apparatus (100) shown in FIG. 4 and, in one embodiment, may be used to excavate holes for the virtual reality imaging system, as described above with respect to FIGS. 1-3.

In embodiments, the database (202) stores information on properties of the system which may include one or more of atmospheric pressure data; geologic formation data; geographic soil type data; location of the target by surface marking data; 3D virtual reality and Ground Penetrating Radar (GPR) data; and system properties data of all pumps, valves, meters, sensors, video, and other equipment in the system. The database may be updated using a variety of communication techniques. In embodiments, the database information is updated on a periodic basis or on a real-time basis.

Global Positioning Satellite (GPS) coordinates may be stored in the database, which may allow a user to store GPS target information. Such information may be gathered from the virtual reality system, site observation, GPR and other scanning, GPS locators, Geographic Information System (GIS), land surveys, improvement and other plans of the project.

The database (202) is communicatively coupled to processing device (204). In embodiments, the processing device (204) includes a digital processor (214), system memory (216), removable storage (218), non-removable storage (220), output devices (222), input devices (224) and communications connections (226). This is only one example of a suitable computing device and is not intended to suggest any limitation as to the scope of use or functionality.

System memory includes volatile memory (such as RAM), non-volatile memory (such as ROM, flash memory, etc.), or some combination of the two. For example, a ROM-based processing device (204) may be used to operate the drilling apparatus (100) with only limited human interaction (e.g., for use in digging post holes), while a RAM-based processor may operate the drilling apparatus (100) in a more controlled fashion to locate underground targets as described above. Storage devices (220) and (218) include, but are not limited to, magnetic or optical disks or tape. Input devices (224) may include touch screens, keyboard, mouse, pen, voice input, etc., while output device(s) (222) may include a display, speakers, printer, etc. In embodiments, no input device is present. Communication connections (226) may include LAN, WAN, point to point, Bluetooth, RF, coaxial cable, or others.

The processing device (204) is operable to receive information related to the drilling apparatus (100) through the communications network (208). For example, information such as visual images captured from down-hole cameras may be routed to an output device (222) of the processing device (204). In other embodiments, no computing device is present and such information is displayed via an analog display or other means.

Other information may be communicated via the communication connections (226). For example, data acquired from instrumentation related to the drilling apparatus (100) may be communicated to the processing device (204) via the network (208). In an embodiment, the signal is first sent to an analog/digital converter (206), where the signal is appropriately converted. Data signals may include information related to the physical properties of soil, valve and piping equipment, the drilling edge, the drilling fluids, and the excavation chamber.

Additionally, information stored in the database may be used to dynamically calculate process parameters or control metrics. For example, pressure and temperature of the drilling apparatus (100) (or subsystems of the drilling apparatus (100)) may be changed using any combination of collected or stored information. As an example, the process control metrics may change based on known and measured soil properties. This is useful as soil properties may change as different geological layers are encountered. For example, three feet of sand may cover six feet of clay, requiring different properties of the excavation chamber for efficient drilling. Tailings and slurry analysis can determine the soil type in real time. Moreover, these changes may be verified by a user. For example, visual inspection of excavated soil may indicate a solid change.

Data regarding the performance of the drilling apparatus (100) may be collected and stored in a database (202) for later analysis.

FIG. 6 illustrates a method (300) of using drilling apparatus (100). The method includes a receive information event (302), a control event (304), a locate target event (306), and a record event (308).

In embodiments, the method (300) beings with receive information event (302) where information regarding a drilling apparatus is received by a user. Such information may include visual inspection using a transparent viewing plate, such as transparent view plate (38). In other embodiments, information is received from process instrumentation via a communications network to a computing device (204). Still in other embodiments, process instrumentation may send information to signaling devices, such as signal lights or noises.

In embodiments, the method (300) proceeds to control event (304) where some portion of the drilling process is controlled based on the information received during receive event (302). For example, a user of a drilling apparatus may decide to shut down the drilling apparatus based on information received from a viewing plate. In other embodiments, the control event is performed by taking no action. Still in other embodiments, control of the system occurs automatically by a computing system (204) sending appropriate signals to a valve or pump of a drilling apparatus in response to received information. For example, a computer may receive signals from a pressure sensor. The computing device may determine that pressure in a line is high compared to a predetermined level based on the received signal from the pressure sensor. Accordingly, the computing device may send a signal to control valves or to the pump motor to stop or slow down in order to reduce the pressure. This and other control systems may be implemented using proportional-integral-derivative controller or other control system now known or later developed. Other process parameters or criteria that may be controlled include temperature and flow rate of process fluids.

In other embodiments, the determination occurs by a user reading a measurement from either a display screen, an analog dial or another indicator. Still in other embodiments, mechanical means such as pressure relief valves are employed.

As described above, the method (300) may optionally include a locate target event (306). In locate target event (306), data acquisition devices are conveyed either through the borehole or through the inner annulus (44) of the cutting head (43) to locate a target that is positioned within the formation either below or laterally adjacent to the borehole. For example, a down-hole camera or a ground penetrating radar system may be used to locate underground targets such as utility lines. The data acquisition devices may also provide GPS coordinates for each detected target.

The process then optionally proceeds to record information event (308) where various process data may be recorded. In embodiments, a user records information by inputting information into an input device of a computing device. The computing device may then store the information in a local or remote database. In other embodiments, a computing device automatically records the received and transmitted signals within a local and/or a remote database. For example, sensor readings may be recorded together with the operational status of other equipment (e.g., pump output and valve positions). Additionally, the computing device may store information obtained from the data acquisition devices that are conveyed through the borehole or the cutting head (43). In this manner, a database connected to the drilling apparatus (or a remote database) may be updated with the GPS or other location information of detected targets such as utility lines. Such a database, in combination with the above-described virtual reality imaging, can be used to produce As Built drawings of the project and would help a utility to mark their lines and protect them from potentially damaging future drilling projects.

Presently preferred embodiments of the present invention have been described with a degree of particularity. These descriptions have been made by way of preferred example and are based on a present understanding of knowledge available regarding the invention. It should be understood, however, that the scope of the present invention is defined by the following claims, and not necessarily by the detailed description of the preferred embodiments. 

I claim:
 1. A method of excavating a borehole extending from a probe entry point to a predetermined underground target point within a formation, comprising the steps of: obtaining three-dimensional coordinates of the predetermined underground target point; operating a cutting head of an excavation probe to initiate the borehole at the probe entry point; determining a real-time three-dimensional position of the cutting head within the formation; displaying the real-time three-dimensional position of the cutting head on a virtual reality display; displaying the predetermined underground target point on the virtual reality display; and directionally guiding the cutting head to the predetermined underground target point utilizing the virtual reality display.
 2. The method of claim 1, wherein the virtual reality display is provided on a visor worn by an operator of the probe cutting head.
 3. The method of claim 1, further comprising the step of operating a down-hole camera to visually verify the underground target point.
 4. The method of claim 1, wherein the step of determining the real-time three-dimensional position of the cutting head within the formation includes calculating at least one of a distance of the cutting head from the probe entry point, a directional bearing of the cutting head from the probe entry point, and an excavation angle of the borehole axis relative to a surface plane.
 5. The method of claim 4, further comprising the step of displaying the borehole axis on the virtual reality display.
 6. The method of claim 1, further comprising the step of guiding the cutting head into contact with an underground target located at the underground target point in order to verify the three-dimensional coordinates or the underground target.
 7. The method of claim 6, wherein the cutting head of the excavation probe comprises a stealth cutting head having a low angle cutting face, and wherein the step of operating the cutting head includes controlling drilling fluids applied to the low angle cutting face to prevent excess drilling fluid from damaging the underground target.
 8. A method of locating and verifying a position of an underground target, comprising the steps of: obtaining initial coordinates of a surface point positioned above the underground target; excavating a vertical access borehole from the surface point to a target depth of the underground target; if the vertical access borehole engages the underground target, verifying a three-dimensional position of the underground target; and if the vertical access borehole does not engage the underground target, then performing the further steps of: lowering a lateral sensor into the vertical access borehole; operating the lateral sensor to locate the underground target and provide three-dimensional coordinates of the underground target; and excavating a second borehole extending from a second surface point toward the three-dimensional coordinates of the underground target; and directing the second borehole into engagement with the underground target to verify the three-dimensional position of the underground target.
 9. The method of claim 8, wherein the step of directing the second borehole into engagement with the underground target includes: displaying the three-dimensional coordinates of the underground target on a virtual reality display; displaying a real-time three-dimensional position of the second borehole on the virtual reality display; and directionally guiding a probe cutting head forming the second borehole to the underground target utilizing the virtual reality display.
 10. The method of claim 9, further comprising operating a down-hole camera to visually verify a condition of the underground target.
 11. The method of claim 9, further comprising recording the three-dimensional coordinates of the underground target within a database.
 12. The method of claim 9, wherein the virtual reality display is provided on a visor worn by an operator of the probe cutting head.
 13. The method of claim 9, wherein the probe cutting head comprises a stealth cutting head having a low angle cutting face, and wherein the step of directing the second borehole into engagement with the underground target includes controlling drilling fluids applied to the low angle cutting face to prevent excess drilling fluid from damaging the underground target.
 14. The method of claim 8, wherein the lateral sensor comprises a Ground Penetrating Radar (GPR) antenna, and wherein the step of excavating the vertical access borehole utilizes a stealth cutting head that forms at least one planar wall surface within the vertical access borehole for engaging the GPR antenna.
 15. The method of claim 8, further comprising the step of verifying that at least one of the initial coordinates and the target depth of the underground target are incorrect in the event that the lateral sensor is unable to locate the underground target, and recording the false reading within a database.
 16. A system for locating and verifying a position of an underground target based on initial surface coordinates and a purported target depth of the underground target, comprising: a first drilling apparatus adapted to excavate a vertical access borehole to the purported target depth within a formation at the initial surface coordinates of the underground target; a lateral sensor adapted to be positioned within the vertical access borehole to determine three-dimensional coordinates of the underground target within the formation; a second drilling apparatus having a cutting head adapted to excavate a second borehole extending from a surface point toward the three-dimensional coordinates of the underground target; and a virtual reality display adapted to display the three-dimensional coordinates of the underground target in relation to a real-time three-dimensional position of the cutting head to directionally guide the cutting head into engagement with the underground target.
 17. The system of claim 16, wherein lateral sensor comprises a Ground Penetrating Radar antenna.
 18. The system of claim 16, wherein the virtual reality display comprises a visor adapted to be worn by an operator of the second cutting head.
 19. The system of claim 16, further comprising: a down-hole camera adapted to be positioned within the second borehole to visually verify the underground target.
 20. The system of claim 16, wherein the first drilling apparatus includes a stealth cutting head having a low angle cutting face, the system further comprising: a computing device for monitoring and controlling a supply of drilling fluid directed to the low angle cutting face and an excavation chamber immediately behind the low angle cutting face of the stealth cutting head to prevent excess drilling fluid from damaging the underground target. 